The paper reports the results of studies concerning the effect of acid
treatment on the physico-chemical properties of zeolitic tuff from Pa
glisa-Roumania. NMR, EPR spectroscopies and X-ray diffractometric anal
ysis of samples enable the location of iron in the zeolitic tuff and p
ermit the determination of sample crystallinity during the acid treatm
ent. Electrical properties of the samples were analysed.